2D-rGO-supported FePc bifunctional nanozyme with enhanced catalytic activity for thiosulfate detection and rhodamine B degradation

Abstract

Exploring novel nanozymes with high activity and stability is necessary in sensing to replace some natural enzymes. Here, iron phthalocyanine (FePc) was supported on two-dimensional (2D) reduced graphene oxide (rGO), synthesizing FePc@rGO nanocomposites by a one-pot method. FePc@rGO nanocomposites not only can catalyze the oxidation of colorimetric substrates, but also can degrade rhodamine B (RhB) with the help of permonosulfate (PMS). With the introduction of rGO, FePc was loaded on their surfaces. Compared with free FePc, FePc supported on rGO has smaller size, resulting in its larger specific surface area. These factors are better for exposing the active sites of catalysts and increasing the mass transfer rate between catalysts and substrates. Therefore, FePc@rGO nanocomposites exhibit enhanced catalytic activity. Based on the oxidase-like activity of FePc@rGO nanocomposites, a sensing platform was constructed for the detection of thiosulfate (S₂O₃²⁻) with a detection limit of 0.124 μM and a detection range of 2–50 μM. In addition, this sensing system can be used for the visual detection of S₂O₃²⁻ by a portable smartphone. Furthermore, the degradation efficiency of FePc@rGO nanocomposites to RhB could be as high as above 94% for just 10 min when the pH ranged from 3 to 10. This work provides an avenue for the synthesis of novel catalysts as multifunctional nanozymes for detection and organic pollutant degradation.